A typical circuit board includes a section of circuit board material (e.g., fiberglass, copper, vias, etc.) and circuit board components attached or mounted to the section of circuit board material. Examples of circuit board components include integrated circuits (ICs) that generate heat during operation. A fan assembly typically generates an air stream that passes over the circuit board components to conduct the heat away from the components. The air stream removes the heat so that the circuit board components do not operate in an unsafe (e.g., relatively high) temperature range that causes the components to perform improperly (e.g., generate a signal incorrectly) or sustain damage (e.g., overheat, burnout, etc.).
Some ICs include heat sinks to facilitate cooling. In general, a heat sink is a flanged metallic device that attaches directly to the package of the IC. As the IC generates heat, heat flows from the IC package to the heat sink, and dissipates into the surrounding air. The air stream generated by the fan assembly then carries the heat away from the location of the IC, thus cooling the IC.
Conventional circuit boards utilize a relatively large number of components that encompass a given amount of surface area or real estate on a component side of the circuit board. As the number of components on the circuit board increase, the amount of real estate available for traces (e.g., electronic connections among the components) decreases. Certain circuit boards include relatively larger circuit board components, such as application specific integrated circuits (ASICs), located on a first side (e.g., solder side) of the circuit board, opposite to a second side (e.g., component side) of the circuit board. By locating the circuit board components on the first (e.g., solder) side of the circuit board, manufacturers increase the amount of surface area or real estate available for traces on the second (e.g., component) side of the circuit board.
In order to cool the circuit board component when mounted to the first side of the circuit board, heat sinks have been conventionally utilized. For example, one such conventional heat sink includes a receptacle that fastens to a support assembly where the support assembly attaches to and supports the circuit board. The heat sink also includes an adjustable member that engages the receptacle and is movable relative to the receptacle in order to control a distance between the adjustable member and the circuit board component. The heat sink can therefore be moved to a position (e.g., in full contact with a circuit board component package, into contact with thermal transfer material that contacts the circuit board component package, etc.) that allows the heat sink to transfer heat from the circuit board component to another structure, such as the support assembly. Such heat transfer allows cooling of the circuit board component during operation even when the component resides in a location having limited space (e.g., an approximate 5 mm space between the circuit board and support assembly).
Heat pipes have been conventionally used for cooling processors (e.g., CPU's) associated with computerized devices. Heat pipes are devices that transmit heat from a first location, such as an area of relatively high temperature, to a second location, such as an area of relatively low temperature. For example, in laptop or mobile computers having processors generating power levels under 20 watts, low wattage heat pipes connect between the processor and a heat exchanger to remove the heat generated by the processor, thereby dissipating the heat from and cooling the processor. In another example, in workstation computers having processors generating power levels of up to 75 watts, heat pipes, combined with cooling fins from approximately 3 to 6 inches in height, remove heat from the processor. In such an arrangement, the heat pipe and cooling fin combination uses an air stream or airflow to cool the cooling fins, thereby lowering thermal resistance of the cooling fins. Thermal pouches have also been used to cool computer processors. The thermal pouch has a flexible bag, such as formed of a plastic material, for example, filled with a fluid. Once secured to a processor, the thermal pouch conforms to the shape of the processor and transfers heat away from the processor.